The Rotor BSA 30 Ceramic bottom bracket allows the use of a 30mm spindled Rotor 3D plus crank on a frame with an English threaded bottom bracket. So you can get the stiffness of a 30mm oversize spindle even with a threaded bottom bracket shell. The only catch is you have to use the 3D Plus crank - the spindle on a standard BB30 crank is too short.
Like all Rotor product the precision boutique machining of these BSA30 cups is simply beautiful exuding craftsmanship with perfect threads. The Enduro Ceramic bearings are noticeably smoother than stock outboard bearings. Rotor includes instructions and an outboard cup installation tool.